PH increase question

[perform02]

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The addition of solution B to solution A causes the PH of solution A to increase by three units. If the hydrogen ion concentration in solution A was 4.5*10^-4 to begin with, then what was it after the addition of solution B?

I thought the answer would be 4.5*10^-1, while the answer key says 13.5*10^-4?


plus, does anyone know how we decide the maximum number of double bonds for a hydrocarbon molecule?


THANKS!

 

[Corpseman]

The addition of solution B to solution A causes the PH of solution A to increase by three units. If the hydrogen ion concentration in solution A was 4.5*10^-4 to begin with, then what was it after the addition of solution B?

I thought the answer would be 4.5*10^-1, while the answer key says 13.5*10^-4?


plus, does anyone know how we decide the maximum number of double bonds for a hydrocarbon molecule?


THANKS!

My first thought was 4.5*10^-7, which would increase the pH from 3.35 to 6.35.

 

[JonPrePharmD]

My first thought was 4.5*10^-7, which would increase the pH from 3.35 to 6.35.

I got the same.

[H+] Solution A before addition of B = 4.5*10^-4
pH= -log(4.5*10^-4) = 3.35

3.35+3=6.35

[H+] = 10^-pH = 10^-6.35 = 4.5*10^-7

For the max # double bonds I just divide # of carbons by 2. That's the way I've always done it.

 

[Pharmrx12]

It seems like the pH of A initial (4.5*10^-4) was multiplied by 3 units = 13.5*10^-4.!!

 

[JonPrePharmD]

It seems like the pH of A initial (4.5*10^-4) was multiplied by 3 units = 13.5*10^-4.!!

4.5*10^-4 is conc. of H+

It's my understanding for every 1 unit increase in pH, hydrogen ion concentration increases 10 fold....by increase I mean becoming more basic.

Thus,
pH of 1, [H+] = 1.0x10^-1
pH of 2, [H+] = 1.0x10^-2

So you would think 4.5*10^-4 would be something *10^-7 so already the answer key is wrong unless something was left out by the poster of the thread or it's worded so strangely I don't understand..